In the agrochemical industry, farmers use various fertilizers to impart macronutrients to plants either by application to the soil or application to plant leaves. Nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur are macronutrients that must be supplied to the plants and soil manually by farmers. In many crops, the amount of nitrogen supplied is critical to the overall quality and growth of the crop. Nitrogen is typically supplied in the form of nitrogenous, i.e., nitrogen precursor-containing, fertilizer compounds, such as urea, ammonium nitrate, or ammonium phosphate fertilizer compounds. Due to the high water solubility of these salts, however, applied nitrogen values may be lost due to run-off and leaching of the nitrogenous fertilizer compounds. Once applied, the nitrogenous fertilizer compounds are typically degraded, for example, by microorganisms present in the soil, to nitrogenous species such as NH4+, NO2−, NO3−, and ammonia gas, that may be even more readily lost through evaporation, run-off, and leaching than the fertilizer compounds themselves. If degradation of the fertilizer compounds occurs at a rate that is faster than the nitrogenous degradation products can be used by the plants, then the nitrogen values in the degradation products are at increased risk of being lost.
Nitrification and/or urease inhibitors are of potential use in delaying degradation of fertilizer compounds and thereby reducing losses of nitrogenous degradation products that would otherwise occurred in the absence of the inhibitors. The use of nitrification and/or urease inhibitors in combination with nitrogenous fertilizer compounds tends to increase the amount of time the nitrogen source remains in the soil and available for absorption by the plants, which tends to increase the effectiveness of the fertilizer and positively impact crop yield and quality.
Aqueous end use fertilizer solutions are typically prepared in the field by diluting commercially available concentrated fertilizer compositions with water. Commonly used concentrated fertilizer compositions include concentrated ammonium nitrate compositions, such as, for example, UAN 18, UAN 28, UAN 30 and UAN 32.
Dicyandiamide is potentially useful as a nitrification inhibitor in such aqueous end use fertilizer compositions, but has very low solubility (about 41 grams per liter (“g/l”)) in water and so is difficult to incorporate into the aqueous end use fertilizer compositions, particularly under field conditions